This is called Repetitive Strain Injury(RSI) and there many ways that you could possibly reduce the risk of such injuries. You need to just do a little research on ergonomics and find good equipment to deal with it. One thing I am going to say that if you are constantly getting in pain then it could cause permanent damage, so consult your DR. It sounds obvious to me that your chair is in a bad position for you to relax… I fall victim to bad posture all the time in favour of being able to control the PC better lol… Humans are not designed to sit down all the time, so you shouldn’t really be sat down a lot and you need to get up and do something. But seriously, if it is frequent then you should consult a DR as you can cause permanent damage…